1. Field of the Invention
The present invention relates generally to starter motors and, more particularly, to an overhang starter motor for starting a vehicle engine.
2. Description of the Prior Art
Overhang starter motors for starting vehicle engines are well known. As shown in FIG. 2, such an overhand starter motor generally consists of a d.c. motor 1 for generating rotary power to start an engine and a pinion moving cylinder 3 slidably fitted over the output shaft or extended portion 2 of an armature shaft 1a and having a pinion portion 3a at the front end and a clutch inner member 4a of an overrunning clutch 4 at the rear end. The output shaft 2 is supported by the front frame 5 via the pinion moving cylinder 3 such that the pinion portion 3a is movable through an opening 6 of the front frame 5 according to the sliding movement of the pinion moving cylinder 3.
The overrunning clutch 4 is slidably fitted over the output shaft 2 such that the rear cylindrical portion of a clutch outer member 4b engages with a helical spline 7 of the output shaft 2 so that the rotary power is transmitted to the clutch inner member 4a via a roller 4c. The circumferential surface of the pinion moving cylinder 3, which is integral with the clutch inner member 4a, forms a sliding surface 3b slidably supported by a bearing 8 which is fitted in the front frame 5.
In such an overhang starter motor, there can be a delay in return of the pinion moving cylinder 3 or noise generated when current to the d.c. motor 1 is cut off. In some engines, the rotation of the pinion moving cylinder 3 by the pinion portion 3a is so fast that the over running clutch 4 is burned. Although the cause for such incidents is unclear, there is a great demand for solving such problems.